Sputtering apparatus and recording medium for recording control program thereof

ABSTRACT

Disclosed is a sputtering device wherein a target ( 2 ) is disposed offset with respect to a substrate ( 7 ), wherein said sputtering device can ensure a uniform amount of deposition, even when a substrate support holder ( 6 ) has a low number of rotations of several rotations to several tens of rotations, and the amount of deposition is extremely small, such as a film thickness of 1 nm or less. A control unit ( 11 ) is provided to perform control using input of the values of a total whole number of rotations N and a fractional number of rotations α such that X=N+α (where N is the total whole number of rotations and is a positive whole number, and α is the fractional number of rotations and is a positive pure decimal) and, by input of the value of a deposition time T such that the rotational velocity V (rps) of the aforementioned substrate support holder ( 6 ) satisfies V·T=N+α when the total number of rotations of the aforementioned substrate support holder ( 6 ) is X, during the deposition time of T (seconds) for particles sputtered onto the surface of the aforementioned substrate ( 7 ) where a film is to be formed.

TECHNICAL FIELD

The present invention relates to a sputtering apparatus used fordepositing a film forming material on a film forming surface of asubstrate in, for example, a manufacturing process of electronicequipment such as a semiconductor device, a display device, etc. and arecording medium such as a magnetic recording medium on which a programused to control the drive of the sputtering apparatus is recorded.

BACKGROUND ART

For example, it is known to use a slanting sputtering apparatus in orderto deposit a film forming material uniformly on a film forming surfaceof a substrate by using a target smaller than the substrate in amanufacturing process of a semiconductor device. In the slantingsputtering apparatus, a sputtering cathode for supporting the target anda substrate support holder for supporting the substrate are arrangedsuch that a surface of the target is positioned slantly with respect tothe film forming surface of the substrate. The film forming material isdeposited by flight of sputtering particles to the film forming surfaceof the substrate from an oblique direction by rotating the substratesupport holder to rotate the film forming surface of the substrate in agiven plane (see, for example, Patent References 1, 2, 3, 4 and 5).

Meanwhile, since there are demands for a highly sophisticatedsemiconductor device, a technology of depositing a very small amount ofmaterial to provide a uniform film thickness of 10 nm or less is beingdemanded. For example, a technology of depositing MgO in thickness of 1nm or less is being demanded for a transistor to lower power consumptionby adjusting a threshold voltage (see, for example, Nonpatent Reference1).

PRIOR ART REFERENCES Patent References Patent Reference 1: JapanesePatent Laid-open Publication No. 2000-265263 Patent Reference 2:Japanese Patent Laid-open Publication No. 2005-340721 Patent Reference3: Japanese Patent Laid-open Publication No. 2006-237371 PatentReference 4: Japanese Patent Laid-open Publication No. 2006-233283Patent Reference 5: WO2006/077827 Nonpatent Reference

Nonpatent Reference 1: IEDM Tech. Dig., by N. Mise et al., p. 527 (2007)

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

When a very small amount of film forming material is deposited by asputtering apparatus to form a film having a film thickness of 10 nm orless, and particularly 1 nm or less as described above, the depositionis completed in a short deposition time of several seconds to severaltens of seconds.

Meanwhile, when it is considered to maintain a high vacuum atmosphere tokeep the quality of the film, the rotational velocity of the substratesupport holder is limited to about 100 rpm according to the presentindustrial technology. Therefore, when the deposition time is severalseconds to several tens of seconds, the number of rotations of thesubstrate support holder is about several tens of rotations αt most, andeven if the number of rotations is increased to try to improve theuniformity of a deposition amount, it is difficult to increase furtherthe number of rotations.

The present invention provides a sputtering apparatus ensuring theuniformity of a deposition amount even when the substrate support holderhas a low number of rotations of several rotations to several tens ofrotations and the amount of deposition is extremely small to provide afilm thickness of 10 nm or less and particularly 1 nm or less.

Means for Solving the Problems

The sputtering apparatus according to the invention has a sputteringcathode for supporting a target and a substrate support holder forsupporting a substrate. The sputtering cathode and the substrate supportholder are disposed such that a vertical line running through the centerpoint of the target and a vertical line running through the center pointof the substrate are mismatched with each other among vertical lines toa plane including the film forming surface of the substrate.Specifically, there are a case that the film forming surface of thesubstrate and the surface of the target are parallel to each other andtheir center points are displaced from each other and a case that thefilm forming surface of the substrate and the surface of the target arenot parallel to each other, and the positions of their center points aredisplaced from each other. The substrate support holder is rotatable ona rotating axis which is perpendicular to the film forming surface ofthe substrate. And, a control unit is provided to control a rotationalvelocity V (rps) of the substrate support holder so as to satisfy:

V·T=N+α

by inputting the value of a deposition time T and the values of a totalwhole number of rotations N and a fractional number of rotations α,which are expressed as:

X=N+α (where, N is a total whole number of rotations which is a positiveinteger, and α is a fractional number of rotations which is a positivepure decimal)

when it is determined that a total number of rotations of the substratesupport holder is X during the deposition time T (seconds) of sputteringparticles onto the film forming surface of the substrate.

As a preferable embodiment, the sputtering apparatus according to theinvention is provided with a power supply unit for supplying power tothe sputtering cathode, wherein the deposition time T is a time from thestart to end of supplying the power from the power supply unit to thesputtering cathode.

As a preferable embodiment, the sputtering apparatus according to theinvention is also provided with a power supply unit for supplying powerto the sputtering cathode and an openable/closable shutter disposedbetween the sputtering cathode and the substrate support holder, whereinthe deposition time T is a time when the power is supplied from thepower supply unit to the sputtering cathode and the shutter is open.

The recording medium according to the invention is a recording medium onwhich recorded is a program for controlling a rotational velocity V(rps) of a substrate support holder of a sputtering apparatus which hasa sputtering cathode for supporting a target and the substrate supportholder for supporting a substrate, which are disposed to have a verticalline running through the center point of the target and a vertical linerunning through the center point of the substrate mismatched with eachother among vertical lines with respect to a plane including a filmforming surface of the substrate, and the substrate support holder isrotatable on a rotating axis perpendicular to the film forming surfaceof the substrate. And, the recording medium according to the inventionrecords thereon the program for controlling the rotational velocity V ofthe substrate support holder by calculating

V·T=N+α

based on the value of a deposition time T and the values of a totalwhole number of rotations N and a fractional number of rotations α,which are expressed as:

X=N+α (where, N is a total whole number of rotations which is a positiveinteger, and α is a positive pure decimal)

when it is determined that the total number of rotations of thesubstrate support holder is X during the deposition time T (seconds) ofsputtering particles onto the film forming surface of the substrate.

As a preferable embodiment, the sputtering apparatus and the recordingmedium according to the invention include that the deposition time T is1 to 400 seconds, the total whole number of rotations N is 1 to 100, therotational velocity V of the substrate support holder is 0.016 to 3.5rps, and the fractional number of rotations α is 0.2 to 0.8.

EFFECTS OF THE INVENTION

According to the invention, a deposit film having a film thickness of 10nm or less such as a gate insulating film or a multilayer magnetic filmand particularly a deposit film having a film thickness of 1 nm or lesscan be deposited uniformly on substantially the entire area of thesubstrate.

As a result, the present invention can provide a magnetic memory devicesuch as a high-performance semiconductor device or a TMR (TunnelingMagneto Resistance) element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view showing an example of thesputtering apparatus according to the invention.

FIG. 2 is a first timing chart showing a timing of start and end pointsof a deposition time T.

FIG. 3 is a second timing chart showing a timing of start and end pointsof the deposition time T.

FIG. 4 is a third timing chart showing a timing of start and end pointsof the deposition time T.

FIG. 5 is a fourth timing chart showing a timing of start and end pointsof the deposition time T.

FIG. 6 is a sectional view schematically showing an arrangementrelationship between a substrate support holder and a sputtering cathodeaccording to the invention.

FIG. 7 is a sectional view schematically showing another arrangementrelationship between a substrate support holder and a sputtering cathodeaccording to the invention.

FIG. 8 is a diagram showing the distribution of a deposition amount ofMg of Example 4.

FIG. 9 is a diagram showing the distribution of a deposition amount ofMg of Comparative Example 1.

FIG. 10 is a graph showing relationships between deviation angles β(fractional numbers of rotations α) and uniformity of deposition amountsaccording to Examples 1 to 4 and Comparative Example 1.

MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a schematic sectional view showing an example of thesputtering apparatus according to the invention.

In the sputtering apparatus shown in FIG. 1, a sputtering cathode 3 forsupporting a target 2 is disposed at a ceiling portion of a vacuumvessel 1. A substrate support holder 6 which is attached to a rotatingaxis 5 rotated by a rotation drive mechanism 4 is arranged at the centerof a bottom surface portion of the vacuum vessel 1. The substratesupport holder 6 supports horizontally a substrate 7, and the rotatingaxis 5 is disposed perpendicular to a film forming surface (surfaceexposed toward the target 2) of the substrate 7. Therefore, thesubstrate 7 can be rotated with the rotations of the substrate supportholder 6 in a state that the film forming surface is positioned in aprescribed plane.

The substrate support holder 6 is rotated at least for a deposition time(film forming time) T (seconds) when the sputtering particles from thetarget 2 are deposited on the film forming surface. Since the rotationalvelocity V (rps) of the substrate support holder 6 is readilycontrolled, it is desirably kept at a fixed level during the depositiontime T. But, the rotational velocity V can also be varied during thedeposition time T. For example, it can also be determined during thedeposition time T to have a low rotational velocity in the early periodand a fast rotational velocity in the latter half period and converselya fast rotational velocity in the early period and a low rotationalvelocity in the latter half period. In addition, the rotational velocityV of the substrate support holder 6 can also be varied at a rate of adirect function or a quadratic function during the deposition time T.

In the example shown in FIG. 1, the sputtering cathode 3 and thesubstrate support holder 6 are disposed such that the surface (thesurface exposed toward the substrate 7) of the target 2 is inclinedagainst the film forming surface of the substrate 7. Therefore, thesputtering particles directed from the target 2 to the film formingsurface of the substrate 7 are deposited by entering the film formingsurface from an oblique direction.

A DC power source 8 is connected as a power supply unit to thesputtering cathode 3. Prescribed DC power (e.g., 1 W to 1000 W,preferably 10 W to 750 W) can be applied from the DC power source 8 tothe sputtering cathode 3. An RF power source can also be used as a powersupply unit instead of the DC power source 8.

A shutter 10 which can be opened and closed by a shutter drive mechanism9 is arranged between the sputtering cathode 3 (target 2) and thesubstrate support holder 6 (substrate 7). When the shutter 10 is open,the sputtering particles generated from the target 2 can be deposited onthe film forming surface of the substrate 7. But, when the shutter 10 isclosed, flight of the sputtering particles generated from the target 2to the film forming surface of the substrate 7 is blocked to prevent thedeposition of the sputtering particles onto the film forming surface ofthe substrate 7.

A control unit 11 controls the rotations of the substrate support holder6, on and off of the DC power source 8 and open and close of the shutter10. The control unit 11 comprises a CPU (central processing unit) 12, arecording medium 13 on which a control program is recorded and an inputportion 14. As the control unit 11, a general-purpose computer can beused. The recording medium 13 is a medium on which a program describedlater can be recorded in a callable state, and specifically anon-volatile memory such as a hard disk, a magnet-optical disk, aflexible disk, a flash memory, MRAM or the like usable for thegeneral-purpose computer can be used. As the input portion 14, akeyboard, a mouse, a touch panel, a voice-input means and the like canbe used.

The control unit 11 controls the rotational velocity V (rps) of thesubstrate support holder 6 by inputting the deposition time T togetherwith the values of the total whole number of rotations N and thefractional number of rotations α, which are expressed as:

X=N+α (where, N is a total whole number of rotations which is a positiveinteger, and α is a fractional number of rotations which is a positivepure decimal),

when it is determined that the total number of rotations of thesubstrate support holder 6 is X during the deposition time T of thesputtering particles onto the film forming surface of the substrate 7.

For further description, a first digital value related to the depositiontime T, a second digital value related to the total whole number ofrotations N of the substrate support holder 6 within the deposition timeT and a third digital value related to the fractional number ofrotations α are inputted from the input portion 14 into the CPU 12 andrecorded temporarily in it. These digital values can also be recorded onthe recording medium 13 and read if necessary.

The CPU 12 of the control unit 11 is connected to the rotation controlmechanism 4, the DC power source 8 and the shutter drive mechanism 9.The CPU 12 of the control unit 11 controls the operations of the DCpower source 8 and the shutter drive mechanism 9 at the required timingand also controls the operation of the rotation control mechanism 4 inaccordance with the above drive timing to control the rotationalvelocity V (rps) of the substrate support holder 6.

An operation command to and the control of the rotation drive mechanism4 are performed according to the first, second and third digital values,which are temporarily recorded in the CPU 12, by reading the controlprogram recorded on the recording medium 13. The operation command toand the control of the rotation drive mechanism 4 are executed bycalculating:

V·T=N+α

from the individual values of the deposition time T, the total wholenumber of rotations N and the fractional number of rotations α which aregiven as the first, second and third digital values and rotating thesubstrate support holder 6 at the determined rotational velocity V forthe prescribed deposition time T. In other words, the sputteringapparatus of the present invention controls the rotational velocity V ofthe substrate support holder 6 such that the total number of rotations Xof the substrate holder 6 during the deposition time T is not an integerbut has the fractional number of rotations α without fail.

The deposition time T according to the invention is determined from athickness of a deposit film to be formed on the substrate 7 and adeposition speed (deposition thickness per unit time of the film formingmaterial to the substrate 7) of the used sputtering apparatus accordingto the invention. The deposition speed can be determined by performing apreliminary film forming experiment under the same conditions as thosefor formation of the deposit film on the substrate 7. The total wholenumber of rotations N can be selected arbitrarily in a range that anexcessive load is not applied to the rotation drive mechanism 4depending on the ability of the rotation drive mechanism 4. And, thefractional number of rotations α can be determined by performing thepreliminary film forming experiment with the fractional number ofrotations α varied by adjusting the rotational velocity V of thesubstrate support holder 6 with the total whole number of rotations Nfixed to obtain the fractional number of rotations α at which a depositfilm having a film thickness as uniform as possible can be formed.

For example, the start and end points of the deposition time T can bedetermined as on/off timing of the power supply unit (e.g., DC powersource 8), open/close timing of the shutter 10, or a combination ofon/off timing of the power supply unit and open/close timing of theshutter 10 to the sputtering cathode 3.

FIG. 2 to FIG. 5 show first to fourth timing charts each showing atiming of start and end points of the deposition time T. These timingcharts are described additionally referring to FIG. 1.

The first timing chart of FIG. 2 shows a case that the deposition time Tis determined by timings of opening and closing the shutter 10. The CPU12 of the control unit 11 first introduces a sputtering gas into thevacuum vessel 1 of the sputtering apparatus with the shutter 10 in aclosed state and turns “on” the DC power source 8 to supply a constantpower to the sputtering cathode 3 to start discharge, thereby generatingplasma at the front surface of the target 2. After that, the shutterdrive mechanism 9 operates to open the shutter 10. The time when theopening operation of the shutter 10 is terminated (time when the shutter10 is fully opened) is the start point of the deposition time T. And,when the deposition time T has elapsed from the termination of theopening operation of the shutter 10, the shutter drive mechanism 9 isoperated again to close the shutter 10. In this case, the time ofstarting the closing operation of the shutter 10 is the end point of thedeposition time T.

The second timing chart of FIG. 3 shows a case that the deposition timeT is determined by the on/off timing of the power supply unit (e.g., DCpower source 8) to the sputtering cathode 3. This timing chart can beapplied to a device not provided with the shutter 10 and a case that thesputtering apparatus is driven with the shutter 10 kept open. In thesecond timing chart, the time when the CPU 12 of the control unit 11introduces a sputtering gas into the vacuum vessel 1 of the sputteringapparatus and turns “on” the DC power source 8 is the start point of thedeposition time T, and the time when the DC power source 8 is turned“off” later is the end point of the deposition time T.

The third timing chart of FIG. 4 shows a first example of determiningthe deposition time T by a combination of the on/off timing of the powersupply unit (e.g., DC power source 8) and the open/close timing of theshutter 10. The start point of the deposition time T in this thirdtiming chart is same to the start point in the first timing chart. Inthe third timing chart, when the deposition time T has elapsed from thestart point, the DC power source 8 is turned off with the shutter 10 inthe open state, and then the shutter 10 is closed. And, the time whenthe DC power source 8 is turned “off” is the end point of the depositiontime T.

The fourth timing chart of FIG. 5 shows a second example of determiningthe deposition time T by a combination of the on/off timing of the powersupply unit (e.g., DC power source 8) and the open/close timing of theshutter 10. The CPU 12 of the control unit 11 first introduces asputtering gas into the vacuum vessel 1 of the sputtering apparatus withthe shutter 10 in the closed state and operates the shutter drivemechanism 9 to open the shutter 10. Then, the DC power source 8 isturned “on” to supply a constant power to the sputtering cathode 3 tostart discharge, thereby generating plasma at the front surface of thetarget 2. The start point of the deposition time T in this fourth timingchart is the time when the DC power source 8 is turned “on”. And, theend point of the deposition time T is same to the end point of the firsttiming chart.

The deposition time T according to the invention is determined as a timein which the necessary deposit film thickness is obtained, and theinvention is particularly effective for formation of a thin deposit filmand effective when the deposit film thickness is 10 nm or less andparticularly 1 nm or less. In other words, the present invention iseffective for formation of a deposit film having a short deposition timeT, and the deposition time T according to the invention is preferably 1to 400 seconds, and more preferably 1 to 30 seconds.

The rotational velocity V of the substrate support holder 6 according tothe invention may be obtained by a general rotation control mechanism 4and preferably in a range of 0.016 to 3.5 rps, and more preferably in arange of 0.05 to 2 rps. Since a very low-speed rotation requires aspecial system for the rotation mechanism and the control mechanism, itis preferably 0.016 rps or more from the viewpoint of the cost. Tomaintain a high vacuum atmosphere by a simple sealing mechanism, therotational velocity V is preferably 3.5 rps or less. And, it is morepreferably 0.05 rps or more for more stable operation. The substrate 7is placed on the substrate support holder 6, which is accelerated from astationary state, then the film formation is started when the substratesupport holder 6 reaches a desired rotational velocity. After the filmformation is terminated, the substrate support holder 6 is deceleratedto return to the stationary state. Therefore, when the rotationalvelocity is increased, an influence on a throughput (the number ofsubstrates per unit time processed by the apparatus) due to accelerationand deceleration time of the substrate support holder 6 increases, andwhen it is tried to decrease the acceleration and deceleration time, anexcessive force is applied to the mechanism, and a maintenance cycle isdecreased. Therefore, it is more preferable that the substrate supportholder 6 has a rotational velocity V of 2 rps or less.

The total whole number of rotations N according to the invention becomesan integer of 1 or more, and generally in a range of 1 to 100 rotations,and preferably in a range of 1 to 50 rotations.

The fractional number of rotations α according to the invention isdetermined by the preliminary film forming experiment as describedabove. For example, it is determined as 0.1 rotation (deviation angleβ=36 degrees), 0.2 rotation (deviation angle β=72 degrees), 0.5 rotation(deviation angle β=180 degrees), 0.15 rotation (deviation angle β=54degrees), 0.151 rotation (deviation angle β=54.36 degrees) or the like.

Generally, the fractional number of rotations α is preferably 0.1 to 0.9rotation, and more preferably 0.2 to 0.8 rotation. The above deviationangle β denotes an amount of angular deviation with the rotating axis 5at the center which is generated between the time of starting rotationsand the time of stopping rotations αt one point on the substrate supportholder 6.

The material used for the target 2 of the invention includes, forexample, a metal such as Hf (hafnium), Mg (magnesium), La (lanthanum),Zr (zirconium), Ta (tantalum), Ti (titanium), Al (aluminum), Co(cobalt), Fe (iron), Ni (nickel), Ru (ruthenium), Cu (copper), Pt(platinum), Mn (manganese) or Cr (chromium), an oxide such as magnesiumoxide, hafnium oxide, lanthanum oxide, silicon oxide, tantalum oxide orchromium oxide, a carbide such as silicon carbide, or the like, but theyare not exclusively limited. The target 2 is preferably set to have adiameter smaller than that of the substrate 7. In a preferableembodiment, the diameter of the target 2 is in a range of 0.1 to 0.9time, and preferably 0.3 to 0.7 time, larger than the diameter of thesubstrate 7.

As the substrate 7 used in the present invention, for example, a siliconsubstrate, a gallium arsenide substrate, an AlTiC substrate, a glasssubstrate, a stainless substrate, an aluminum substrate, a plasticsubstrate and the like can be used, but they are not exclusivelylimited.

In the example shown in FIG. 1, the sputtering cathode 3 and thesubstrate support holder 6 are disposed such that the surface (surfaceexposed toward the substrate 7) of the target 2 is inclined with respectto the film forming surface of the substrate 7. But, the arrangement ofthe sputtering cathode 3 and the substrate support holder 6 according tothe invention is not limited to the above. The film forming surface ofthe substrate 7 and the surface of the target 2 may be arranged to beparallel to each other when a vertical line running through the centerpoint of the target 2 and a vertical line running through the centerpoint of the substrate are mismatched with each other among verticallines with respect to a plane including the film forming surface of thesubstrate 7. Arrangement examples of the sputtering cathode 3 and thesubstrate support holder 6 according to the invention are describedbelow with reference to FIG. 6 and FIG. 7.

FIG. 6 and FIG. 7 are sectional views each schematically showing anarrangement relationship between a substrate and a target according tothe invention, and members common to those of FIG. 1 are denoted by likereference numerals.

In the drawings, 102 denotes a target; 103 a sputtering cathode; 106 asubstrate support holder; 107 a substrate; (a) a vertical line(substrate vertical line (a)) running through a center (o) of thesubstrate 107 among vertical lines with respect to a plane including thefilm forming surface of the substrate 107; and (b) a vertical line(substrate vertical line (b)) running through a center (p) of the target102; and a shift amount (l) is a distance between the substrate verticalline (a) and the substrate vertical line (b). And, (c) in FIG. 7 is avertical line (target vertical line (c)) running through the center (p)of the target 102 among vertical lines with respect to a plane includingthe surface of the target 102.

In the arrangement example shown in FIG. 6, the sputtering cathode 103and the substrate support holder 106 are arranged such that the surfaceof the target 102 and the film forming surface of the substrate 107 areparallel to each other and the substrate vertical line (a) and thesubstrate vertical line (b) are not a common linear line but positionedseparate from each other and are mismatched with each other. Thesputtering cathode 103 and the substrate support holder 106 may bearranged such that even when the substrate vertical line (b) is arrangedto become a linear line running inside the outer peripheral edge of thesubstrate 107, the substrate vertical line (b) becomes a linear linerunning outside the outer peripheral edge of the substrate 107. Theshift amount (l) is preferably 50 to 800 mm, more preferably 100 to 500mm, and much more preferably 150 to 400 mm. And, a distance from thecenter (p) of the target 102 to the plane including the film formingsurface of the substrate 107 along the substrate vertical line (b) ispreferably 50 to 800 mm, more preferably 100 to 500 mm, and much morepreferably 150 to 400 mm.

In the arrangement example shown in FIG. 7, the sputtering cathode 103and the substrate support holder 106 are arranged such that the surfaceof the target 102 is not parallel to the film forming surface of thesubstrate 107, and the substrate vertical line (a) and the substratevertical line (b) are not a common linear line but positioned separatefrom each other and are mismatched with each other. A crossing angle θbetween the substrate vertical line (a) and the target vertical line (c)is preferably 1 to 45 degrees, and more preferably 5 to 35 degrees. Inthis arrangement example, the sputtering cathode 103 and the substratesupport holder 106 may also be arranged such that even when thesubstrate vertical line (b) is arranged to become a linear line runninginside the outer peripheral edge of the substrate 107, the vertical line(B) becomes a linear line running outside the outer peripheral edge ofthe substrate 107. The shift amount (l) is preferably 50 to 800 mm, morepreferably 100 to 500 mm, and much more preferably 150 to 400 mm. And, adistance from the center (p) of the target 102 to the plane includingthe film forming surface of the substrate 107 along the substratevertical line (b) is preferably 50 to 800 mm, more preferably 100 to 500mm, and much more preferably 150 to 400 mm.

When the substrate 107 has a circular shape like a silicon wafer, thecenter point (o) of the substrate 107 is the center of the circularshape, and when it has a square shape like a glass substrate, it is anintersection of two diagonal lines. When it has a shape other than thecircular or square shape, the center of gravity is determined to be thecenter point (o). They are also same for the target 102.

EXAMPLES Examples 1 to 4, Comparative Example 1

Using the sputtering apparatus shown in FIG. 1, Mg (magnesium) wasdeposited on a substrate. Film forming conditions are as follows. Adeposition speed was determined by performing a preliminary film formingexperiment for forming a deposit film of Mg. Specifically, depositionamounts were measured at 17 points in an area excluding an outerperipheral portion of 5 mm of a Si wafer having a diameter of 300 mm onwhich the Mg deposit film was formed in the same manner as the methoddescribed below, and the average of the 17 deposition amounts divided bythe deposition time (film forming time) was determined as the depositionspeed. And, a total whole number of rotations N was selected as ageneral value for ability of the rotation drive mechanism 4 of the usedsputtering apparatus.

(1) Deposition speed: 0.01418 nm per second(2) Target Mg film thickness: 0.2 nm(3) Deposition time T: 14.1 seconds (0.2÷0.01418=14.1)(4) Total whole number of rotations N: 23 rotations.(5) Total number of rotations X and fractional number of rotations α

Example 1

Total number of rotations X=23.20 rotations, fractional number ofrotations α=0.20 rotation (deviation angle β=72 degrees)

Example 2

Total number of rotations X=23.40 rotations, fractional number ofrotations α=0.40 rotation (deviation angle β=144 degrees)

Example 3

Total number of rotations X=23.60 rotations, fractional number ofrotations α=0.60 rotation (deviation angle β=216 degrees)

Example 4

Total number of rotations X=23.80 rotations, fractional number ofrotations α=0.80 rotation (deviation angle β=288 degrees)

Comparative Example 1

Total number of rotations X=23.0 rotations, fractional number ofrotations α=0 (deviation angle β=0 degree)

(6) Arrangement of sputtering cathode 103 and substrate support holder106: Crossing angle θ=32.7 degrees, shift amount (l)=276 mm(7) Power supply unit for sputtering cathode 3: DC power source 8 (powerof 50 W)

Mg was deposited on the substrate 7 in Examples 1 to 4 and ComparativeExample 1 as described below, except that the fractional number ofrotations α was varied as shown in the above (5).

The values of the above conditions (3) to (5), namely the values ofdeposition time T, total whole number of rotations N and fractionalnumber of rotations α, were inputted into the CPU 12 of the control unit11. Calculation was made by the CPU 12 such that the rotational velocityV (rps) of the substrate support holder 6 met V·T=N+α, and based on thecalculated result, the rotational velocity V of the rotation drivemechanism 4 was controlled together with the opening/closing action ofthe shutter 10 and the on/off operation of the DC power source 8.

First, a Si (silicon) wafer having a diameter of 300 mm was placed asthe substrate 7 on the substrate support holder 6, and the interior ofthe vacuum vessel 1 was evacuated to 5.3×10⁻⁷ Pa.

As the target 2, metal Mg having purity of 99.9% was used.

Then, Ar gas was introduced into the vacuum vessel 1 while evacuatingthe vacuum vessel 1 such that the vacuum vessel 1 had a low-pressure Argas atmosphere of 0.1 Pa therein.

When the Ar gas was introduced, the substrate support holder 6 wasstarted to rotate, so that the substrate 7 was rotated together with thesubstrate support holder 6. This rotation was determined to have aconstant rotational velocity V calculated from the values of thedeposition time T, the total whole number of rotations N and thefractional number of rotations α.

The DC power source 8 was turned “on” with the shutter 10 in a closedstate, and power controlled to constant power of 50 W was applied to thesputtering cathode 3 to start a discharge from the target 2 to generateplasma at the front surface of the target 2. The potential of the targetagainst ground potential became negative, positive ions in the plasmaentered the target 2, and sputtering of the target 2 of Mg was started.

In this state, the shutter 10 was operated to open, and Mg was startedto deposit onto the substrate 7. After the sputtering particles of Mgwere deposited on the substrate 7 for a given deposition time T only,the DC power source 8 was turned “off” to block the application of powerto the sputtering cathode 3, and the Mg deposition was terminated. Thedeposition time T was from the termination of the opening operation ofthe shutter 10 to the turn “off” of the DC power source 8, and thedeposition time T was set to 14.1 seconds as shown in the (3) above.During the deposition time T of 14.1 seconds, the substrate supportholder 6 was continued to rotate at the rotational velocity V calculatedas described above.

The obtained Mg film was measured for the Mg deposition amount, and thedistribution of a deposition amount was measured. The deposition amountwas measured by X-ray fluorescence analysis. For the distribution of adeposition amount, the deposition amounts at 17 points in an areaexcluding an outer peripheral portion of 5 mm of a Si wafer having adiameter of 300 mm were measured, and a value three times larger than aratio of a standard deviation to the average value of the 17 depositionamounts was determined as a value of uniformity.

FIG. 8 shows the measured results of the distribution of a depositionamount of Mg when the film was formed in Example 4 [total number ofrotations X=23.80 rotations, fractional number of rotations α=0.80rotation (deviation angle β=288 degrees)], which were standardized andshown at a rate to the average value of the deposition amounts. FIG. 9shows the measured results of the distribution of a deposition amount ofMg when the film was formed in Comparative Example 1 [total number ofrotations X=23.0 rotations, fractional number of rotations α=0(deviation angle β=0 degree)] which were standardized and shown at arate to the average value of the deposition amounts. In addition, FIG.10 is a graph showing a relationship between the deviation angle β(fractional number of rotations α) varied in Examples 1 to 4 andComparative Example 1 and the uniformity of deposition amounts in the Mgfilms obtained in Examples 1 to 4 and Comparative Example 1.

It is seen from FIG. 8 to FIG. 10 that although the total whole numberof rotations N is a small number of rotations such as 23 rotations andthe deposition time T is also short such as 14.1 seconds, thedistribution of the deposition amount can be suppressed by controllingto give the fractional number of rotations α of pure decimal, and theuniformity can be improved.

EXPLANATION OF REFERENCE NUMERALS

-   1: Vacuum vessel-   2, 102: Target-   3, 103: Sputtering cathode-   4: Rotation drive mechanism-   5: Rotating axis-   6, 106: Substrate support holder-   7, 107: Substrate-   8: DC power source-   9: Shutter drive mechanism-   10: Shutter mechanism-   11: Control unit (computer)-   12: CPU (processing unit)-   13: Recording medium-   14: Input portion-   a: Vertical line running through the center of a substrate among    vertical lines with respect to a plane including a film forming    surface-   b: Vertical line running through the center of a target among    vertical lines with respect to a plane including a film forming    surface-   c: Vertical line running through the center of a target among    vertical lines with respect to a plane including a surface of the    target-   o: Center of substrate-   p: Center of target-   l: Shift amount-   θ: Crossing angle

1. A sputtering apparatus, comprising a sputtering cathode forsupporting a target and a substrate support holder for supporting asubstrate, which are disposed to have a vertical line running throughthe center point of the target and a vertical line running through thecenter point of the substrate mismatched with each other among verticallines to a plane including a film forming surface of the substrate, andthe substrate support holder being rotatable on a rotating axis which isperpendicular to the film forming surface of the substrate, wherein: thesputtering apparatus has a control unit for controlling a rotationalvelocity V (rps) of the substrate support holder in a range of 0.016 to3.5 rps to satisfy:V·T=N+α, by inputting the value of a deposition time T in a range of 1to 400 seconds and the values of a total whole number of rotations N ina range of 1 to 100 and a fractional number of rotations α in a range of0.2 to 0.8, which are expressed as:X=N+α (where, N denotes a total whole number of rotations which is apositive integer, and a denotes a fractional number of rotations whichis a positive pure decimal) when it is determined that a total number ofrotations of the substrate support holder is X during the depositiontime T (seconds) of sputtering particles onto the film forming surfaceof the substrate.
 2. (canceled)
 3. (canceled)
 4. The sputteringapparatus according to claim 1, further comprising a power supply unitfor supplying power to the sputtering cathode, wherein the depositiontime T is a time from the start to end of supplying the power from thepower supply unit to the sputtering cathode.
 5. The sputtering apparatusaccording to claim 1, further comprising a power supply unit forsupplying power to the sputtering cathode and an openable/closableshutter disposed between the sputtering cathode and the substratesupport holder, wherein the deposition time T is a time when the poweris supplied from the power supply unit to the sputtering cathode and theshutter is open.
 6. A recording medium on which recorded is a programfor controlling a rotational velocity V (rps) of a substrate supportholder of a sputtering apparatus which has a sputtering cathode forsupporting a target and the substrate support holder for supporting asubstrate, which are disposed to have a vertical line running throughthe center point of the target and a vertical line running through thecenter point of the substrate mismatched with each other among verticallines with respect to a plane including a film forming surface of thesubstrate, and the substrate support holder being rotatable on arotating axis perpendicular to the film forming surface of thesubstrate, wherein: the recording medium records thereon the program forcontrolling the rotational velocity V of the substrate support holder ina range of 0.016 to 3.5 rps by calculating:V·T=N+α based on the value of a deposition time T in a range of 1 to 400seconds and the values of a total whole number of rotations N in a rangeof 1 to 100 and a fractional number of rotations α in a range of 0.2 to0.8, which are expressed as:X=N+α (where, N is a total whole number of rotations which is a positiveinteger, and α is a fractional number of rotations which is a positivepure decimal) when it is determined that the total number of rotationsof the substrate support holder is X during the deposition time T(seconds) of sputtering particles onto the film forming surface of thesubstrate.
 7. (canceled)
 8. (canceled)
 9. The sputtering apparatusaccording to claim 5, wherein the control unit controls the substratesupport holder to rotate it and to maintain at the rotational velocityV, to operate the power supply unit with the shutter in a closed state,and then to operate the shutter to open it.
 10. The sputtering apparatusaccording to claim 9, wherein the control unit controls the power supplyunit to stop its power after the deposition time T elapses from thetermination of the opening operation of the shutter.
 11. The sputteringapparatus according to claim 9, wherein the control unit controls theshutter to start its closing operation after the deposition time Telapses from the termination of the opening operation of the shutter.12. The sputtering apparatus according to claim 6, wherein thesputtering apparatus is provided with a power supply unit for supplyingpower to the sputtering cathode, an openable/closable shutter isdisposed between the sputtering cathode and the substrate supportholder, and the deposition time T is a time when the power is suppliedfrom the power supply unit to the sputtering cathode and the shutter isopen.
 13. The sputtering apparatus according to claim 12, wherein theprogram controls to rotate the substrate support holder and to maintainat the rotational velocity V, to operate the power supply unit with theshutter in a closed state, and then to operate the shutter to open it.14. The sputtering apparatus according to claim 13, wherein the programcontrols the power supply unit to stop its power after the depositiontime T elapses from the termination of the opening operation of theshutter.
 15. The sputtering apparatus according to claim 13, wherein theprogram controls the shutter to start its closing operation after thedeposition time T elapses from the termination of the opening operationof the shutter.